Molecular characterization of metallothionein cDNA of Sparus aurata used for detecting heavy metal pollution along the Mediterranean coast of Israel

Members of the fish family Sparidae are abundant in various continental shelf habitats along the Mediterranean, including relatively clean and polluted areas. The levels of metallothionein (MT)-mRNA in their liver is suggested here as a bioindicator parameter for the detection of heavy metals in Mediterranean marine habitats. A complete MT-cDNA was cloned from the liver of metal-induced Sparus aurata and used to evaluate the MT-mRNA levels in the livers of the abundant coastal sparid species, Lithognathus mormyrus, both after laboratory induction by cadmium and in fish sampled along a pollution gradient at Haifa Bay, the Mediterranean coast of Israel. It is concluded that the MT-mRNA in L. mormyrus liver is a good bioindicator of heavy metal pollution in the marine environment, because of the following: it is heavy metal-inducible; its level is turned off rather rapidly after the elimination of the inducing agents; and it is shown to be correlated to a heavy metal pollution gradient in a natural marine habitat.